Fish Tags Create Dinner Bell Effect

Wednesday 19 November 2014

Seals can listen in on scientific equipment to find a tasty meal, according to research published today (Wednesday November 19, 2014).

Marine biologists at the University of St Andrews have shown that grey seals learn to use sound to their advantage. Marine mammals are sensitive to noise and are exposed to many different types of acoustic signals while swimming at sea. Other scientists have already found that many animals avoid human noise sources. However new research, published in Royal Society journal Proceedings of the Royal Society B, has found that these sounds can also provide interesting information to the animals.

Currently, scientists worldwide are using small tags to mark and study fish at sea. These tags produce ‘pinging’ sounds that allow researchers to track and follow fish. However, grey seals can also hear these pinging tags, and potentially use them as a ‘dinner bell’ for their next meal.

To see if seals listened in on tags, researchers created a maze of boxes to hide fish and measured where the seals were looking. Most boxes were empty, but two had a fish, one with a pinger and one without. Seals found the pinging fish much quicker than the silent one, showing a clear use of the sounds provided by the scientific equipment. The research was carried out by Amanda Stansbury, Thomas Götz, Volker Deecke and Vincent Janik at the University of St Andrews Sea Mammal Research Unit.

Stansbury explained: “The seals found the tagged fish sooner and with less searching than the fish without a tag. This means that the seals learned to use the sound from the pinging tags to find where their food was hidden. This tells us that seals can exploit new sounds, such as fish tags, and use them to their advantage.”

The results show that scientists have to be careful when using acoustic tags to study fish. Stansbury added: “We expect that other marine mammals are similarly able to use such information to find prey. Tagged fish may be more detectable by predators, which could affect the results of fish studies. When we make noise in the sea, we need to consider how animals are affected. Our results show that such effects can be complicated. In our case they were beneficial to the seal but bad for the fish. ”

ENDS

NOTES TO NEWS EDITORS

The University of St Andrews’ Sea Mammal Research Unit (SMRU) provides the UK’s main science capability in the field of marine mammal biology.

The Unit carries out interdisciplinary research into the biology of marine mammals, trains marine mammal scientists through undergraduate and postgraduate teaching, and advise governments, non-governmental organizations and industry on conservation issues.

SMRU is a Natural Environment Research Council (NERC) Collaborative Centre. NERC provided strategic science funding to support this research.